1. Field of the Invention
The present invention generally relates to traffic control systems, and more particularly to, a signal preemption system that prioritizes traffic signal changes to efficiently route an emergency vehicle, and which accounts for the proximity of vehicles as they are also proximate to an intersection having the traffic signal operation preempted.
2. Description of the Related Art
Emergency vehicles, such as fire-fighting engines, ambulances and police cars, generally have the need to cross or pass intersections under the control of traffic signals. This must be accomplished in the least amount of time possible so that the function of an emergency vehicle can be successfully fulfilled. It is generally understood that the more quickly an emergency vehicle can reach the scene of an emergency, the greater are the chances that the victims involved can be helped or successfully treated.
Since the earliest times, emergency vehicles approaching intersections have depended upon sirens, horns, bells or other types of audible and/or visible warning devices to alert other people in the intersection. This has not always proven to be a successful technique, even though it is still the standard mode of operation for emergency vehicles today. Unfortunately, accidents involving emergency vehicles often occur at intersections due to confusion, impaired hearing, inattention, noise conditions or overly-aggressive drivers seeking to clear the intersection before the arrival of the emergency vehicle. Other factors are the speed of the emergency vehicle and the resulting inability of others to react to it, distractions affecting the driver of the emergency vehicle, and the like. Further problems are caused when multiple emergency vehicles are approaching the same intersection. This situation is further complicated when the sirens and other signals from multiple emergency vehicles can be heard within the same area—a combination confusing to both pedestrians and other motorists, as well as the operators of both emergency vehicles. In many cases, due to siren noise and the intensity of focused driving at high speeds through congested areas, emergency vehicle operators are often not aware of other such vehicles in the same area.
During the course of emergency vehicles which are preempting traffic signals enroute to the scene, emergency vehicle drivers can often forget to use their turn signals. If a preemption-equipped emergency vehicle is about to make a left turn, for example, traffic signals to the left of the intersection will not begin their preemption sequence until after the left turn has been made. This may not allow for ample time for the next traffic signal in its path (following the turn) to effectively clear traffic along the route, slowing its response.
While emergency vehicles operate in proximity to each other there is a heightened chance of their colliding due to assumptions made on the part of the operators. A system that will predict the proximity of emergency vehicles at intersections is needed to reduce the likelihood of accidental collisions.
What is needed in the art is a system that can predictively preempt the normal operation of traffic signals and warn emergency vehicle drivers of the proximity of other emergency vehicles in such preempted intersections.